And when Andrade and Zhang were done, they had added two more names to the shockingly long list of Russians going home early from Beijing.

Zhang upset light heavyweight Artur Beterbiev 8-2 on Thursday at Workers' Gymnasium, and Andrade easily stayed on track for a medal with a 14-3 thrashing of Andrey Balanov.

The losses left just six fighters in the field for Russia, which was widely expected to be the games' dominant power over a young Cuban team. Instead, four Russians were picked off in the last two days of preliminary bouts, while Cuba still has nine fighters in the field.

Andrade was far too much for Balanov, who only scored one point - he got two more on a curious penalty against Andrade for ducking. The American's technically superb victory avenged a loss to the 32-year-old Balanov in Russia back in early 2005 when the current world champion welterweight was a raw prospect from Providence, R.I., on his first international trip.

"He was the first person I ever fought over, maybe, 22," Andrade said. "I was real nervous. I'm only 16, I've got no power, I can't hold the guy. I went in there and did my thing, but I learned from it, and it got me to where I am today."

That's one victory from a guaranteed medal, and three wins from gold. He'll fight South Korea's Kim Jung-joo on Sunday for a semifinal place.

Zhang got a few curious points from the judges, but still controlled his fight with another Russian disappointment. Beterbiev, who finished second in last year's championships, didn't score after the first round and seemed to have no strategy to beat his tall, long-armed opponent.

Zhang turned the fight into a hug-a-thon at times, but scored enough on the outside to win.

"I had the psychological advantage, because my opponent is stronger than me, so I have no pressure," Zhang said. "Secondly, my strategy is quite good. I took advantage of my height and kept distance from my opponent."

Chinese welterweight Hanati Silamu also beat overmatched Joseph Mulema of Cameroon 9-4 to advance within one victory of a medal. China, which has never won gold in a sport banned by under Chairman Mao Zedong, has seven boxers still alive in the Olympics - unbelievably, more than the Russians.

At least light welterweight Gennady Kovalev slowed the Russian slide in the evening session with an 11-2 win over Richarno Colin of Mauritius.

Banteaux, who lost to Saunders earlier in the year, fought with precise strategy in the rematch, counterpunching and picking away at his eager teenage opponent. Banteaux showed off his sharper grasp of amateur boxing's idiosyncratic scoring for punches from multiple angles.

Saunders' teammate, light heavyweight Tony Jeffries, opened his Olympics with a victory over Colombia's Eleider Alvarez in a fight that ended in a 5-all tie. Amateur boxing matches are then decided by the highest average of total punches landed, as scored by three of the five judges at ringside.

But Britain lost another medal hope in the evening session when light welterweight Bradley Saunders lost 11-7 to France's Alexis Vastine. Saunders, no relation to his teammate, had beaten Vastine in the world championship quarterfinals last fall on the way to a bronze medal, but was decisively beaten by his sometime training partner.

"It's a big weight off my shoulders, now I know I haven't got a medal," Saunders said. "It's been brilliant coming here, but there's so much pressure with the training and not seeing my family. Now I can be back with my family and live a normal boy's life."

Unheralded Egyptian welterweight Hosam Abdin got the session off to a remarkable start with an 11-10 victory over Thailand's Non Boonjumnong, who finished second at last year's worlds. Abdin hung on in the final two rounds even after his coach was kicked out of his corner for being too vocal.

Boonjumnong's brother, Manus, later opened defense of his light welterweight gold medal in Athens by beating Japan's Masatsugu Kawachi.

"I'm incredibly sad and disappointed," Manus said of his brother's loss. "He has been preparing even better than me. He talked to my parents, and they cried on the phone, but it was destiny that he couldn't get through. I will try to do the best where I am now."